A production energy management system is known for modeling the flow of energy and the flow of products in a plant and evaluating the energy usage condition based on the metered energy usage, the production, and the like. The production energy management system visualizes the current status of the energy consumption, the improvement, and the like, in other words, realizes the “visualization”, clarifies the operation indexes associated with the energy of a factory, and thereby supports the optimization of the energy usage.
For example, a production energy management system described in Patent Literature 1 and Non-Patent Literature 1 collects energy information and production information in a production line and links the energy information to the production information, and thereby calculates the energy consumption, the CO2 emission, the energy cost, the production efficiency, the specific energy consumption and the like, per product or per lot. The specific energy consumption is an index, which is obtained by dividing the energy consumption used for producing products by the production of the products, the input amount of raw materials, the production of interim products, or the like.
As shown in FIG. 14, the linking of the energy information and the production information is performed by associating an energy flow model, which models the energy flow in a plant, with a production flow model, which models the production flow between apparatuses, devices, or the like (collectively referred to as apparatuses).
Processes in a plant may be divided into a batch process and a continuous process based on their production systems. The batch process is a non-continuous process where a series of operations is added and mainly materials having any shape are processed or combined to produce products, such as in a mechanical industry plant.
On the other hand, the continuous process is a process where both materials and products are mainly fluids such as liquid or gas, the materials continuously flow into an apparatus, the materials are continuously processed during flowing through the apparatus, and the products also continuously flow from the apparatus, such as in a petroleum refining plant or a chemical plant.
In the batch process, the relationship is clear between the energy, which is supplied to the apparatus and consumed, and the products in each apparatus, while, in the continuous process, there are some cases where the products include energy as potential heat, a part of the products is circulated in the apparatus or temporarily stored in the apparatus. In addition, there are some cases where a part of products is used as energy.
As shown in FIG. 14, a conventional production energy system defines an energy flow model, calculates electric power energy, steam energy, energy of cold-water, and the like, which are introduced into an apparatus, and thereby calculates the energy consumption. A production flow model is defined and the production is calculated in each apparatus.
Though the calculation method using such a model is suitable for the batch process where the relationship is clear between the energy, which is supplied to the apparatus and consumed, and the products in each apparatus, the calculation method is not suitable for the continuous process where there is a wide range of variations in paths of the products and the consideration for the energy of the products is required.